The objectives of this proposal are to compare the effectiveness of four types of exercise rehabilitation programs designed for patients who are recovering from a myocardial infarction. The study has begun and 20 patients have entered the program. Preliminary results indicate that the expected increments in working capacity have occurred, but a comparison between groups is not possible because of small numbers. Subjects are males who are in the 8th to 16th week after the heart attack and who meet rigid criteria for admission to the study. Each of the experimental groups consist of 20 subjects. The four groups include: Group A - bicycle exercise conducted under supervision in the laboratory, Group B - bicycle exercise conducted mostly at home with only weekly visits to the laboratory, Group C - walking exercise conducted mostly at home with weekly visits to the laboratory, Group D -walking exercise conducted at home from general instructions with no follow-up visits. The eight week exercise programs will be preceeded and followed by evaluations. Groups will be compared for improvement in working capacity, changes in psychological test scores (MMPI), alterations in activity habits, and attitudes toward exercise. The results will assist in defining the contribution of supervision and type of exercise to the results of exercise programs. This information will assist in the conduct of future studies to determine the effectiveness of exercise rehabilitation programs and in the development of clinical exercise programs.